%find the average of the input values until -1 is entered
sumo=0;%running sum for the average
n=0;%counter for how many  elements entered before -1
x=input('enter your value -1 to end')
while(x~=-1)
    sumo=sumo+x
    n=n+1
    x=input('input your next value- -1 to end')
end
if n~=0
    av=sumo/n
end